1. Field of the Invention
The invention relates to a method of producing a magnetic field sensor, whose sensor element is formed by at least one piece of wire comprising amorphous or nanocrystalline ferromagnetic material, whose electrical impedance depends on a magnetic field, the piece of wire being provided with electrically conductive terminals of nonferromagnetic metal. The invention further relates to magnetic field sensors produced by this method.
2. Description of the Related Art
Prior art magnetic field sensors include a piece of wire made of an amorphous, ferromagnetic material, whose electrical impedance is magnetic-field-dependent. Because of this property, it is possible to detect the intensity of a magnetic field by measuring the current flowing through the sensor element. Such magnetic field sensors are used for instance to scan magnetically coded data carriers, which have a plurality of magnetic dipoles located close together. There is a need to be able to detect each of the thus-generated individual magnetic fields separately, so as to be able to pick up the information from the data carrier. Since the individual magnetic fields are thus very close together, there is a need to embody the sensor element with very short lengths, for instance on the order of magnitude of about 100 .mu.m, so that the desired local resolution can be attained.
In the production of such magnetic field sensors, however, the problem arises that sensor elements made from an amorphous or nanocrystalline wire material with the aforementioned dimensions can be electrically connected by soldering only with difficulty if at all. Magnetic field sensors with very short effective lengths thus cannot be produced by conventional methods.
It has become known from Japanese patent disclosure JP 08-323 479A to connect sensor elements formed of amorphous material to the electrical terminals by means of resistance welding. It is disadvantageous, in that process, that resistance welding destroys or damages the amorphous structure of the sensor elements, thereby destroying or affecting the magnetic field dependency of the sensor elements.